Koki Tanaka (?? ?, Tanaka Koki, born November 5, 1985) is a Japanese singer–songwriter, actor and former Japanese idol.
He was a member of Jpop idol boy band KAT-TUN from their debut until September 30, 2013 when his contract with Johnny & Associates (the company that manages KAT-TUN) was terminated.
When he was a member of KAT-TUN, he was recognized as the rapper in the group and has a hip-hop-influenced style.
Out of the other members, Tanaka was most often paired up with Yuichi Nakamaru and they even formed a comedy duo 'TaNaka'.
After leaving Johnny & Associates, Tanaka formed a new rock band called INKT.